31393561 has 2 divisors, whose sum is σ = 31393562. Its totient is φ = 31393560.

The previous prime is 31393559. The next prime is 31393619. The reversal of 31393561 is 16539313.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 29767936 + 1625625 = 5456^2 + 1275^2 .

It is a cyclic number.

It is not a de Polignac number, because 31393561 - 2¹ = 31393559 is a prime.

Together with 31393559, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (31393261) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15696780 + 15696781.

It is an arithmetic number, because the mean of its divisors is an integer number (15696781).

Almost surely, 2^31393561 is an apocalyptic number.

It is an amenable number.

31393561 is a deficient number, since it is larger than the sum of its proper divisors (1).

31393561 is an equidigital number, since it uses as much as digits as its factorization.

31393561 is an evil number, because the sum of its binary digits is even.

The product of its digits is 7290, while the sum is 31.

The square root of 31393561 is about 5602.9957165788. The cubic root of 31393561 is about 315.4618604811.

The spelling of 31393561 in words is "thirty-one million, three hundred ninety-three thousand, five hundred sixty-one".